Robot apparatus, robot controlling method, program, recording medium, and assembly manufacturing method

Abstract

There is provided a robot apparatus which is characterized by comprising: a robot comprising a plurality of motors for driving respective joints and a sensor for obtaining force acting on a hand tip; and a controlling unit for obtaining a torque instruction value for each of the plurality of motors such that a force deviation between the force acting on the hand tip and a force target value becomes small, controlling driving of each of the plurality of motors based on the torque instruction value, and performing a stopping process of decreasing the force target value when a stop order for stopping the robot is received.

What is claimed is: 
     
       1. A robot apparatus comprising:
 a robot comprising a plurality of motors configured to drive respective joints, a sensor configured to obtain force acting on a hand tip, and a sensor configured to obtain a position of the hand tip; and 
 a controlling unit configured to:
 output a respective torque instruction value to each of the motors such that the force acting on the hand tip becomes a force target value, 
 control driving of each of the motors based on the respective torque instruction value, and 
 in a case where a stop order for stopping the robot is received in a stopping process, set the force target value to a decreased force target value, set as a position target value the position of the hand tip at the time when the stop order is received, and output the respective torque instruction value to each of the motors such that the force acting on the hand tip becomes the decreased force target value and the position of the hand tip becomes the position target value. 
 
 
     
     
       2. The robot apparatus according to  claim 1 , wherein, in the case of setting the position target value to the position of the hand tip at the time when the stop order is received in the stopping process, the controlling unit is configured to decrease a stiffness coefficient of the robot. 
     
     
       3. The robot apparatus according to  claim 1 , wherein the sensor configured to obtain the position of the hand tip includes a plurality of sensors configured to detect respective positions of the motors or respective positions of the joints. 
     
     
       4. The robot apparatus according to  claim 1 , wherein:
 the controlling unit is configured to obtain a speed of the hand tip from a value of the sensor configured to obtain the position of the hand tip, and 
 in the stopping process, the controlling unit is configured to set to decrease a speed target value of the hand tip, and output the torque instruction value such that the speed of the hand tip becomes the speed target value. 
 
     
     
       5. The robot apparatus according to  claim 1 , wherein:
 the robot further comprises a sensor configured to obtain a speed of the hand tip, and 
 in the stopping process, the controlling unit is configured to set to decrease a speed target value of the hand tip, and output the torque instruction value such that the speed of the hand tip becomes the speed target value. 
 
     
     
       6. The robot apparatus according to  claim 4 , wherein, in the case of decreasing the speed target value in the stopping process, the controlling unit is configured to decrease a viscosity coefficient of the robot. 
     
     
       7. The robot apparatus according to  claim 1 , wherein the robot further comprises a brake configured to brake each of the joints, and
 the controlling unit is configured to fix each of the joints of the robot by the brake, after the robot is stopped in the stopping process. 
 
     
     
       8. The robot apparatus according to  claim 1 , wherein the controlling unit is further configured to obtain the force acting on the hand tip from values of a torque sensor for obtaining a torque of each of the joints. 
     
     
       9. The robot apparatus according to  claim 1 , further comprising a teaching pendant having a stop order confirming unit configured to transmit the stop order to the controlling unit. 
     
     
       10. A controlling method of a robot which comprises a plurality of joints, a plurality of motors configured to drive the respective joints, a sensor configured to obtain force acting on a hand tip, and a sensor configured to obtain a position of the hand tip, the controlling method comprising:
 outputting a respective torque instruction value to each of the motors such that the force acting on the hand tip becomes a force target value, and 
 controlling driving of each of the motors based on the respective torque instruction value, 
 wherein, in a case where a stop order to stop the robot is received, the force target value is set to a decreased force target value, the position of the hand tip at the time when the stop order is received is set as a position target value, and the respective torque instruction value is output to each of the motors such that the force acting on the hand tip becomes the decreased force target value and the position of the hand tip becomes the position target value. 
 
     
     
       11. A non-transitory computer-readable recording medium on which a program is stored for controlling a robot which comprises a plurality of joints, a plurality of motors configured to drive the respective joints, a sensor configured to obtain forceacting on a hand tip, and a sensor configured to obtain a position of the hand tip, wherein the program comprises code to execute:
 outputting a respective torque instruction value to each of the motors such that the force acting on the hand tip becomes a force target value; and 
 controlling driving of each of the motors based on the respective torque instruction value, and 
 wherein, in a case where a stop order to stop the robot is received, the program executes: 
 setting the force target value to a decreased force target value, and setting as a position target value to the position of the hand tip at the time when the stop order is received, and 
 outputting the respective torque instruction value to each of the motors such that the force acting on the hand tip becomes the decreased force target value and the position of the hand tip becomes the position target value.